Audio processing method, audio processing apparatus, and recording reproduction apparatus capable of outputting voice having regular pitch regardless of reproduction speed

Abstract

A reproduction part reproduced at a changeable speed ratio r. An A/D conversion part A/D converts, based on sampling frequency fi, an audio signal reproduced at a speed different from that upon recording. A block data division part divides audio data based on an attribute possessed by the audio data. An audio data connection part successively interpolates or thins out the divided audio data based on a ratio of 1/r. A D/A conversion part D/A converts the interpolated or thinned-out audio data based on sampling frequency fo. If a relation of fi/fo=r/c is satisfied, the audio signal is outputted as a sound of high quality constantly synchronized with an image signal and having a pitch which does not change irrespective of the changeable speed ratio r at which the image signal is reproduced.

What is claimed is:  
     
       1. An audio processing method of, when reproducing, at a reproduction speed different from that at which an audio signal have been recorded in a recording medium, the audio signal on the recording medium, adjusting the pitch of the reproduced audio signal, the method comprising the steps of: 
       performing A/D conversion, at a sampling frequency f i , of the audio signal that has been reproduced from the recording medium;  
       performing analysis processing on audio data that has been obtained by the A/D conversion according to the attribute thereof;  
       dividing the audio data into block units each having a prescribed time width according to data that has been obtained by the analysis processing;  
       performing a series of processings of performing interpolation or thinning processing on the audio data in divided block units if necessary to thereby make data length thereof I/r greater and thereby produce output audio data;  
       performing D/A conversion, at a sampling frequency f o , of the thus-produced output audio data to thereby output a sound synchronized with an image; and  
       setting the respective sampling D/A conversion of the audio data to thereby produce an audio signal, and the changeable speed ratio r may satisfy prescribed conditions.  
     
     
       2. An audio processing method according to  claim 1 , wherein as the prescribed conditions, when the sampling frequencies f i  and f o  and the changeable speed radio r satisfy the relationship of f i /f o =r, there is used the sampling frequency f i  which is represented by an expression f i =r·f o ; and when the sampling frequencies f i  and f o  and the changeable speed ratio r are in the relationship of f i /f o ≠r, there is used the sampling frequency f i  that is represented by an expression f i =r·f o /c that includes a sampling frequency conversion coefficient c. 
     
     
       3. An audio processing method according to  claim 2 , when performing digital signal processing on the audio data that has been obtained by performing A/D conversion, at the sampling frequency f i , of the audio signal that has been reproduced from the recording medium at the changeable speed ratio r, the digital signal processing comprising the steps of: 
       monitoring time data of the audio signal read out from the recording medium and time data of the output audio data that has been obtained through the performance of the series of processes to thereby correct time non-coincidence that occurs between the audio signal and the output audio data.  
     
     
       4. An audio processing apparatus for, when reproducing, at a reproduction speed different from that at which an audio signal has been recorded in a recording medium, the audio signal on the recording medium, adjusting the pitch of the reproduced audio signal, the audio processing apparatus comprising: 
       A/D conversion means ( 3 ) for performing A/D conversion, at a sampling frequency f 1 , of the audio signal that has been reproduced from the recording medium;  
       analysis processing means ( 5 ) for performing analysis processing on audio data that has been obtained by the A/D conversion according to the attribute thereof;  
       block data division means ( 6 ) for dividing the audio data into block units each having a prescribed time width according to data that has been obtained by the analysis processing;  
       output audio data production means ( 11 ) for performing a series of processings of performing interpolation or thinning processing on the audio data in divided block units if necessary to thereby make data length thereof 1/r greater and thereby produce output audio data;  
       audio output means ( 12 ) for performing D/A conversion, at a sampling frequency f o , of the thus-produced output audio data to thereby output a sound synchronized with an image; and  
       sampling frequency setting means for setting the respective sampling frequencies f i  and f o  so that the sampling frequency f i  used when performing A/D conversion, the sampling frequency f o  used when performing D/A conversion of the audio data to thereby produce an audio signal, and the changeable speed radio r may satisfy prescribed conditions.  
     
     
       5. An audio processing apparatus according to  claim 4 , wherein 
       as the prescribed conditions that are set by the sampling frequency setting means, when the sampling frequencies f i  and f o  and the changeable speed radio r satisfy the relationship of f i / f o =r, there is used the sampling frequency f i  which is represented by an expression f i =r≠f o ; and when the sampling frequencies f i  and f o  and the changeable speed ratio r are in the relationship of f i / f o ≠r, there is used the sampling frequency f i  that is represented by an expression f i =r·f o /c that includes a sampling frequency conversion coefficient c.  
     
     
       6. An audio processing apparatus according to  claim 5 , wherein 
       the output audio data production means ( 11 ) comprises means for monitoring time data of the audio signal read out from the recording medium and time data of the output audio data that has been obtained through the performance of the series of processes to thereby correct time non-coincidence that occurs between the audio signal and the output audio data.  
     
     
       7. A recording and reproduction apparatus comprising the audio processing apparatus according to  claim 6 . 
     
     
       8. A recording and reproduction apparatus comprising the audio processing apparatus according to  claim 5 . 
     
     
       9. A recording and reproduction apparatus comprising the audio processing apparatus according to  claim 4 .